Medical laboratories increasingly rely upon automated assay equipment in order to handle large numbers of assays efficiently in terms of time and cost, and further to increase the reliability of such assays by decreasing the amount of human intervention involved in such assays. However, this reduction in human intervention necessitates a corresponding increase in equipment and devices which ensure the accurate performance of such automated assays. In particular, regulatory agencies responsible for oversight of such testing are reluctant to approve certain forms of automated equipment absent enhanced monitoring and error reporting devices.
Assay equipment currently in use is commonly programmed for withdrawal of a desired reagent in preparation for execution of an assay. While such programmed aspirations are typically accurate, there remains the possibility that a reagent source has run dry though the assay equipment continues to aspirate from the empty reagent container, giving a "short shot" of reagent. Further, while an initial indication that reagent exists in a respective container prior to aspiration may be provided, equipment does not currently detect the evacuation of a supply of reagent during an aspiration. Finally, reagent aspiration equipment in existing automated assay apparatus does not provide the capability to detect an occlusion or an incorrect flow rate in real time or errors from a line break.
Optical verification systems are presently used to measure the transmittance of light through a tube as affected by the contents of the tube. Such transmittance detectors include a light source disposed opposite a light sensor on either side of a tube and are primarily useful for detecting and identifying the contents of a tube at any given moment, and do not find utility in confirming a volume of aspirated liquid.